This 2 arm study will compare the effect on hemoglobin response of Mircera and epoetin beta, in patients with chronic renal anemia who are on dialysis. Eligible patients will be randomized to receive either Mircera (0.4 micrograms/kg i.v. every 2 weeks) or epoetin beta (3 times weekly, according to approved labelling). The anticipated time on study treatment is 3-12 months, and the target sample size is 100-500 individuals.